No, it does not bounce all over the place ...

The author, Abby Lowell, and her husband, David Lowell, walk the Perseverance Trail in June of 2008 while she was pregnant with her first child. This trail, which extends 3.5 miles up the valley, is wide and provides stable footing suitable for most users.

Despite the imagery a jogging mom and her belly may conjure, the baby inside is, in fact, not jostled around like clothes in a dryer.

Friends and relatives, those more forward than most, have inquired about what the baby must be experiencing as I’m running up and down mountain trails around town.

“It must feel so weird! Doesn’t it just bounce all over the place?”

Nah. It’s a myth. And like many myths this one deserves to be de-bunked.

I talked to Kristin Hock, a certified direct entry midwife at the Juneau Family Health and Birth Center, who said the baby experiences more of a rocking motion than the jostling-up-and-down some might envision.

“The baby is insulated by quite a bit of amniotic fluid,” Hock said.

And like the body’s vital organs, the baby is cradled by multiple layers of abdominal muscle, which provide support during increased physical activity.

Perhaps this is why babies are soothed by that same rocking motion once born.

Another myth: Pregnant women should keep their heart rate under 140 beats per minute when exercising.

“It really depends on the base fitness level of the mother,” she said.

One thing that is true about heart rate, Hock said, is that as the pregnancy progresses — i.e. as the mother and baby put on more weight — heart rates during exercise will naturally increase. This is purely because the mom has to work harder to jog down that trail or hike up that hill.

“What I’ve found,” Hock said, “is women naturally decrease their level of exercise as the pregnancy progresses. This is especially true once they reach the third trimester.”

The American Congress of Obstetricians and Gynecologists has also abandoned the under-140 recommendation. Today the organization recommends 30 minutes of exercise a day during pregnancy for most women, without any specific heart rate limits.

Hock said it really comes down to intuition.

“I believe women can learn a lot by just listening to their bodies,” she said. “It takes putting pride aside along with the idea that ‘I used to be able to do this.’”

This means adopting a level of peace with your abilities — and your limitations. After all, moms do know best.

Fact: Baby gets first dibs on nutrition. But is this also true for oxygen during exercise?

“Great question,” Hock said.

Yes, baby gets first-pick of everything that mom puts in her body. This includes vital nutrients, vitamins, minerals and fluids.

But Hock said this may not hold true for oxygen during exercise.

“When a mom is exercising, her muscles are readily using oxygen on an as-needed basis,” she said. “It’s likely that if a mom becomes oxygen deprived as a result of too much exertion, the baby will also be deprived.”

The moral? Take it easy. If you can hold a conversation while staying active, you’re likely in the clear. But if you feel out-of-breath, light-headed or have blurred vision — stop, rest and find a shady place to relax.

Another fact: Pregnant women should avoid overheating.

Yes, those hot tubs, steam rooms and saunas could be just the ticket for the aching back and tired legs of a mom-to-be, but they are absolutely not a good idea. Overheating can also happen when exercising in hot or humid weather.

According to ACOG, an elevated internal temperature of 101 degrees F or higher can cause birth defects in babies during the first trimester.

So don’t exercise for long periods of time when the weather is hot, humid or both. Choose areas that are shaded or breezy and make sure to carry water. A good rule to follow: Drink one glass of water every 20 minutes during a workout.

• This week, my trail of choice is the Perseverance Trail, which begins downtown on Basin Road. This time of year the tourist crowds are thin and the trail freshly cleared. This trail is not only noted as one of the three most historically significant trails in Alaska, but it is also known as “Alaska’s First Road.” Once used by Native Alaskans as a trail to access goat hunting, fishing and berry picking, the trail became a road in the 1880s for miners. Each day workers would head up the road to multiple mining operations including the famous Perseverance Mine and the Alaska-Juneau Mine, which was famed for being one of the largest gold-producing mines in the world during that time. Artifacts of the mining times still remain. A keen eye will spot rusted pipes trailside and moss-covered rail ties partially buried underfoot. Most eye-catching is the large “glory hole” which remains in Silverbow Basin, near the end of the trail. In spring, before vegetation obscures the view, this massive hole is easily seen. Flanked by Mount Roberts to the south and Mount Juneau to the north, this trail is one of the most picturesque in Juneau. Overall, the trail, which extends 3.5 miles into the valley, is firm and wide. Workers with the City and Borough of Juneau and Trail Mix Inc. have recently cleared debris from winter rock slides and the snow pack has receded deep into the valley. Anyone looking to head to the end of the trail should be prepared to traipse through snow for about a half mile or more. Despite this, the trail makes for a nice spring outing that can be catered to activity levels of all types.

• Remember, everyone is different. Make sure to check with your doctor or midwife before beginning an exercise program. Contact Outdoors editor Abby Lowell at abby.lowell@juneauempire.com.